PRELP Protein Inhibits the Formation of the Complement Membrane Attack Complex

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Abstract

PRELP is a 58-kDa proteoglycan found in a variety of extracellular matrices, including cartilage and at several basement membranes. In rheumatoid arthritis (RA), the cartilage tissue is destroyed and fragmented molecules, including PRELP, are released into the synovial fluid where they may interact with components of the complement system. In a previous study, PRELP was found to interact with the complement inhibitor C4b-binding protein, which was suggested to locally down-regulate complement activation in joints during RA. Here we show that PRELP directly inhibits all pathways of complement by binding C9 and thereby prevents the formation of the membrane attack complex (MAC). PRELP does not interfere with the interaction between C9 and already formed C5b-8, but inhibits C9 polymerization thereby preventing formation of the lytic pore. The alternative pathway is moreover inhibited already at the level of C3-convertase formation due to an interaction between PRELP and C3. This suggests that PRELP may down-regulate complement attack at basement membranes and on damaged cartilage and therefore limit pathological complement activation in inflammatory disease such as RA. The net outcome of PRELP-mediated complement inhibition will highly depend on the local concentration of other complement modulating molecules as well as on the local concentration of available complement proteins.

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Subject classification (UKÄ) – MANDATORY

  • Other Basic Medicine
  • Rheumatology and Autoimmunity
Original languageEnglish
Pages (from-to)8092-8100
JournalJournal of Biological Chemistry
Volume287
Issue number11
Publication statusPublished - 2012
Publication categoryResearch
Peer-reviewedYes

Bibliographic note

The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Protein Chemistry (013017510), Connective Tissue Biology (013230151)

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